Questions tagged [blockchain]

This tag should be used for questions pertaining to the blockchain. The blockchain is a list of all transactions that have occurred using the Bitcoin currency. It consists of blocks which are linked to each other, and each block consists of transactions. DON'T USE THIS FOR THE SERVICE NAMED 'blockchain.info'!

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Can a miner just introduce a block full of valid predetermined transactions in the blockchain and get rewarded?

My question is - let's say a miner has control over a certain number of bitcoin addresses. He creates a block containing small transactions to and fro from these accounts ahead of time in advance and ...
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IBD problem: Reindexing blocks and syncing starts over every time I shut and open Core

I am currently doing IBD in segments due to logistical reasons, but each time I safely shut down Core and unplug my hard drive (HDD, 1TB) and then plug it back in and start up Core, it starts in 2009 ...
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26 views

Is there a way to know at any point in time T how many BTC exist that were bought at time t<T?

What I would like to find out is whether for a specific time in the past, we can know the number of BTC that exist today and were bought at this time. The discrete time can be the time of block ...
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Does the btc price depend on the reward?

Hey guys if you answer this question that I am keeping from months ill be happy. Does the actual bitcoin price depend on the mining profitability? So is it more profitable mine when the price is ...
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1answer
37 views

How to monitor Bitcoin address for new transactions?

I have some generated Bitcoin addresses which I want to monitor for newly received transactions, I have a full node but I don't want to import those addresses to the node's wallet. I don't want to use ...
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1answer
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Improve uniqueness of block for nonce creation

I am going through online Blockchain course and in the course, they have mentioned that uniqueness of a block is defined using hashes with leading zeros as well as timestamp. Since, in the training, ...
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1answer
40 views

Problem with using blockchain for E-Shopping

I have a confusion with blockchain concepts. Blockchain is immutable. So we can have problems in using blockchain for shopping websites. Because if we use it for retail, people have a habit to return ...
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1answer
48 views

Is Bitcoin and Litecoin blockchains compatible?

While Bitcoin is the first cryptocurrency out there and is deemed to be the "gold" of cryptocurrencies, Litecoin is considered to be the "silver" of cryptocurrencies and the first follower of Bitcoin. ...
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2answers
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Does a trusted blockchain import from BitcoinCore require that chainstate and blocks be from the same source?

Can the chainstate folder from a pruned node be used with the blocks folder from a full node to provide the full blockchain? Assume that both nodes have been running for months. If the blocks folder ...
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1answer
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What is the SPV Mining Exploit?

Can anyone explain this simply? I am not finding enough explanation exactly on this type of attack. If possible, add some additional reading to your answer so that I can understand more.
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When will I receive bitcoins

Today I sent bitcoin to my bitcoin core wallet. I used an address under recieve bitcoins. The transaction has been cleared on the blockchain for several hours but is not showing up in my wallet. ...
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1answer
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Bitcoin not received since 3days now [closed]

Two different bitcoin payment was sent I sent into one Wallet Address requested, But only one came into my wallet successfully. But I am yet to receive the second one, and when I try to look it up on ...
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Will this bitcoin mining strategy work?

I'm new to bitcoin, and my knowledge of bitcoin is quite garbled and messy (I have only a vague understanding of Satoshi's original white paper for bitcoin......) I've been reading up on bitcoin ...
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Bitcoind Bitcoin-cli in Win 10. Why wallet balance is negative inspite Full Sync and progress = 1.000000?

I am running bitcoind since 3 month and it's fully Sync. I still see negative wallet balance. I have re indexed it many times with no result. would you please help me fin out what is wrong? Negative ...
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Accidentally sent BCH instead of BTC to a BTC address (Block chain) [duplicate]

I've accidentally sent BCH from Coinbase to a BTC address of Block chain. Both accounts belong to me. Is there any way to recover it? Please help me.
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1answer
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When does a miner get the reward?

Let's suppose that a miner mines a block and adds it to the blockchain. When it gets the reward ? I suspect that first of all the other nodes have to verify that its proof of work is correct and it's ...
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2answers
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bitcoin back-end blockchain storage

bitcoin uses blockchain so blockchain is peer to peer, every peer stores the data so I wonder where does the data of all the bitcoins is stored? who is peer in case of bitcoin? so that peer gets ...
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How to set up a private Bitcoin network with low mining difficulty

I wish to set up a two-miner private bitcoin network. The miners need to compete for the hash power and the block generation interval is also set to be 10 mins. I found some tutorials about regtest ...
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1answer
30 views

What if the blockchain saved space by trimming input txs on each transaction?

At each block there is a determined set of unspent transaction outputs. Each new transaction specifies the unspent outputs it's going to spend in the format tx_id:output_index. tx_id is 32 bytes. If ...
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What are some good solutions for analyzing Bitcoin script patterns?

I'm interested in analyzing the Bitcoin blockchain for occurrences of particular scripts and spending patterns. What are some good solutions for this? An ideal solution would let me filter ...
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1answer
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mining Blockchain Blocks

What if a miner starts to generate a new block hash based on trans data,latest block hash , timestamp and nonce , then in the middle of the work a new block has been added by another miner. in this ...
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2answers
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How Bitcoin mining contributes to confirmations?

Based on my knowledge I know (maybe wrong) when a miner is doing hash, he is inputting any arbitrary values, in order to get a value that can be hashed into something with certain preceding zeros. ...
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2answers
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How can I print these information using this library?

I want to know how through using this library I can print information about the current block that the world mine right now and I mean by that: Version, Previous Block, Merkle Root, Time, Bits, and ...
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1answer
52 views

Is the ordering of blocks in the rev*.dat files same as the blk*.dat files?

I understand that blk*.dat files save the blocks in the order it gets them from it's peers. Is the rev*.dat files in the same order as the blk*.dat files? For example, would the 400th magicbyte in ...
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What can blockchain do that normal databases systems won't?

Aside from cryptocurrencies, what advantages may blockchain(either public or private) have and real life use cases that can be more useful implemented in blockchain over traditional databases based ...
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1answer
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Understand double spending through an example

Let’s suppose you have 1 BTC which you try to spend twice. You made the 1 BTC transaction to a merchant (Transaction T1). Now, you again sign and send the same 1 BTC on another Bitcoin address to try ...
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1answer
43 views

Fork and Longest Chain Rule

At the same time, A and B succeed in resolving the "Proof of work" challenge and both add a new block to their local blockchain, then they propagate the new blockchains to other nodes. I have 2 ...
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1answer
35 views

Mining process in a blockchain

Let's consider a blockchain. They mining nodes are listening to transactions and every one is building is own block. Due to latency and other issues, every miner is probably building a different block,...
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2answers
392 views

Does every node has a whole copy of the blockchain?

As i read here, in a blockchain "each node the has a copy of all transactions ever made". This to me seems impossible, bitcoin exists for a long time, and the memory size of the intere blockchain ...
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1answer
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When exactly do the transactions get validated?

I have some gaps in my understanding to the life cycle of the transaction that I want someone to help me fill them specially with the validation. What I understand about the life cycle with my ...
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1answer
22 views

Can bitcoind and btcd share a datadir?

I've already fully synced the blockchain with btcd, can I point bitcoind at the same datadir and use its contents?
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5answers
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How do I recover from a cryptocurrency scam?

I lost about $45,000 to crypto investment scam just recently. The company posed as an investment company that could deliver a certain percentage in returns if you deposit your Bitcoin with them. At ...
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1answer
84 views

Is mining a fair mechanism in blockchain network?

As we know, propagation of a new block in blockchain network has some delay and many nodes receive the new block later. so if it is that the first one who finds the nonce properly wins the block can ...
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1answer
27 views

Does getblockcount return the correct block count when running in prune mode?

I am currently running a bitcoin node with prune=550. The getBlockCount from $ bitcoin-cli getblockcount does not match https://blockexplorer.com/api/status?q=getBlockCount. As I understand it, the ...
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2answers
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Bitcoin mining process

Can someone please explain these fuzzy understanding? I am trying to implement my proper demo application of blockchain, but now I discover that many concepts are not that clear.. 1- how do miners in ...
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0answers
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Which Bitcoin simulator can i use where changes in nonce size is possible?

I want to run a Bitcoin simulation in which I can have double nonce running in a loop on the block header, and I can also change the nonce sizes. which simulator can I use for this?
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Configure esplora to point to the bitcoind servers ip address

I have 2 servers running: Ubuntu 18.04 running bitcoind daemon (v0.18.1 full blockchain synchronized) Ubuntu 18.04 running esplora (the local single page website works, but it has no data from the ...
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1answer
51 views

Why one miner can dig out many blocks continually in one moment?

I am new to bitcoin and blockchain, I browed the website just now. There is a question confusing me, I find that one miner dig out blocks many times even in one hour. For example, this miner dig out ...
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1answer
56 views

Why Block Chain not Transactions Chain? [closed]

I believe that, for some people, the term Block is a sort of holy notion. However, there exist yet some block-free blockchains such as Libra (Sometimes referred to as Zuck Buck). Unlike previous ...
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1answer
59 views

How to verify virgin bitcoin

I am willing to acquire bitcoin without transaction history (virgin bitcoin) at a premium. How do I tell that the bitcoins I receive do not have any prior transactions (except of the mining one)? What ...
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2answers
71 views

Why is my bitcoin wallet keep telling me: there was a problem sending your transaction uneconomical UTXO requested

That is what I keep receiving when I try to sent my bitcoin to another wallet address ...
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1answer
49 views

What are some other uses for blockchain instead of money? [closed]

What has blockchain been used for aside from money in the 10 years its been around? I know things like etherium exist, but They don't seem be going anywhere, most of its value seams to come from the ...
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2answers
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Wondering about the viability of a Hardware Wallet

I want to roll my own hardware wallet using a USB stick. I have some concerns: Do I need to download the entire blockchain in order to create a new wallet? Do I need to download and store the entire ...
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1answer
103 views

Why Block Chain not Block Tree?

Why is the Blockchain intended to be a chain and not a tree? Why do orphaned blocks get trimmed off? Would you please provide a detailed answer.
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1answer
44 views

How does Bitcoin utilize cryptography and secure hash algorithm (SHA) to link records in the blockchain?

I am wondering how Bitcoin uses cryptography and secure hash algorithm such as SHA256 to link the records in the blockchain. And if possible I think it will give me a better understanding if there is ...
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0answers
43 views

Lost Transaction from Blockchain.com to Electrum

This link, https://www.blockchain.com/btc/tx/a081d03519bc0f1dcf4ac391da6f54d4d6091c458530b620f96eca5c1c5a3511, shows the transaction was delivered to the address "1Mv4fi8UdVhbfm9iLx2Bf8xhDrMv9sZSyD" ...
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1answer
35 views

Does the chain become computationally more expensive to validate over time?

Since there is only one chain per coin, doesn't that mean it becomes computationally more expensive to validate the chain the older the coin is and the longer the chain becomes?
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1answer
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Race attack with transaction fees

let's say I run a simple race attack (say in a restaurant). I transfer BTC to the restaurant but seconds before (or after) I send the very same coins to myself. To make this deal more likely for ...
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Getting Started with a Hello World Node.js App making an API call to bitcoin.org

I have been reading around trying to find where/how you can attach a SHA256 or MD5 hash (i.e. a small chunk of data) to a Bitcoin transaction, which led to OP_RETURN, but I have yet to see exactly how ...
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1answer
60 views

Who can predict that a benign attacker has 51% hash rate of the system?

In the Bitcoin network, suppose that there is an attacker who has 60% hash-rate (hr) and then other users have 40% hr. Therefore, it is obcioust if other users generate any new block, attacker can ...